The rumens of sheep and cattle commonly contain ciliate Protozoa belonging to numerous genera. The biochemical study of these organisms has been hampered in the past by the difficulty of separating the different types from bacteria, and from one another, in sufficient quantity. The conventional bacterial pure-culture techniques have not so far proved applicable to these organisms, and investigators have therefore had to rely mainly upon alterations to the ruminant's diet, and various manipulations of the rumen liquor in vitro, in attempts to obtain suspensions of individual types of Protozoa. A technique of considerable value in this field was originated by Eadie & Oxford (1957), who found that many species of Protozoa could be eliminated from the sheep rumen by emptying and thorough washing of that organ. In a number of sheep treated in this way, only the smaller species of the oligotrich ciliate Entodinium survived the emptying procedure. It was further found (J. M. Eadie, personal communication, 1958) that when the diet of a treated sheep was altered by including a moderate amount of starchy foods, the numbers of entodinia present in the rumen increased to such an extent that suspensions of mixed Entodinium species, free from other Protozoa, and almost free from bacteria, could readily be prepared from the rumen liquor. Because Entodinium can, under many feeding regimes, be the predominant protozoal genus in the rumen, and because the biochemistry of these organisms has not been studied previously, the present investigation was undertaken. Some of our observations have already been reported briefly (Abou Akkada, Hobson & Howard, 1959). MATERIALS AND METHODSSheep as source of entodinia. The single sheep (no. 105) which served throughout these experiments had previously had its rumen fauna partially removed by the method of Eadie & Oxford (1957), and thereafter was kept isolated from other ruminants. Before the present work was commenced it had been inoculated with Dasytricha ruminantium, but during our experiments only very small numbers * Part 2: Howard (1959b). of this organism were present. In addition to a feed of hay (450 g.) morning and afternoon, the sheep was offered daily 450 g. of a concentrates ration, approximately threequarters of which consisted of ground maize and crushed oats.Preparation of protozoal suspensions. Samples of rumen liquor were withdrawn 3 hr. after the concentrates meal, strained through gauze and mixed in a separating funnel with an equal volume of the bicarbonate buffer solution described below (cf. Oxford, 1958). All manipulations and incubation of protozoa were carried out at 380. During incubation for 1 hr. the entodinia settled to the bottom of the funnel as a grey-white layer, which was run off into boiling tubes containing the buffer solution. From this stage onwards the buffer solutions used always contained chloramphenicol (50,ug./ml.) to suppress bacteria. After threefold washing by decantation, the protozoa formed a clean white layer in the bottom of the tubes. Micr...

Background: Africa is in an orphan-care crisis. In Zimbabwe, where one-fourth of adults are HIVpositive and one-fifth of children are orphans, AIDS and economic decline are straining society's ability to care for orphans within their extended families. Lack of stable care is putting thousands of children at heightened risk of malnourishment, emotional underdevelopment, illiteracy, poverty, sexual exploitation, and HIV infection, endangering the future health of the society they are expected to sustain.

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A sulfate-reducing bacterium has been isolated in pure culture from sheep rumen contents. Its properties agree in all respects tested with those ascribed to Desulfovibrio desulfuricans. The populations observed (about 108/ml) are sufficient to account for published rates of ruminal sulfide production.

Few programmes for sub-Saharan Africa's 12.3 million children orphaned by AIDS have focused on their high risk for psychosocial problems. As groundwork for supporting orphans' healthy development, this study describes the preparation, grief, and memorial experiences and the physical and psychosocial well-being of 144 double orphans and 109 single orphans in rural eastern Zimbabwe. Most received no preparation or orphan-specific support for mourning and emotional recovery. On measures of physical and psychosocial well-being, orphans did more poorly than 87 non-orphaned classmates, perhaps reflecting the combined interaction of economic disadvantage and orphan status. Financial hardship was most severe among single orphans. Double orphans' responses suggested perceptions of isolation, lack of support and personal difference. Distress was greatest among younger orphans (<13 years). Given the importance of emotional health to child and societal development, scaled-up financial assistance should incorporate programmes to help children prepare for and recover from the loss of their parents.

A study of the hydrolysis of some soluble pentosans by suspensions of sheep-rumen bacteria was previously reported (Howard, 1957). It was shown that the mixture of bacteria normally present in the rumen is able, by removal of arabinose side chains if present, and by apparently random breaking of the xylan chain, to hydrolyse the pentosans completely into their constituent monosaccharides. The next step in this investigation was to examine pure cultures of those organisms of the rumen flora which are active in pentosan decomposition. From a number of such cultures which have been isolated in this Laboratory, two were selected for detailed study. One was Bacteroides amylogenes (Doetsch, Howard, Mann & Oxford, 1957), isolated from sheep rumen on a medium containing xylose.The other, which bears the number II in our Laboratory collection, was a strain isolated from bovine-rumen contents on a medium containing wheat-flour pentosan, and tentatively assigned to the genus Butyrivibrio (Bryant & Small, 1956).A brief description of this organism is given in the Appendix to this paper.Preliminary experiments showed that intact cells from pentosan cultures of each of these bacteria vigorously hydrolysed the pentosan, and attention was then turned to the preparation of active cell-free materials. The properties of such preparations are the subject of this paper. Attempts have been made to separate the component enzymes of the pentosan-hydrolysing complex, and to determine their properties and some of the factors controlling the production of them by the bacteria.MATERIALS AND METHODS Bacterial cultures. The strain of Bacteroides amylogenes used was that described by Doetsch et al. (1957). The Butyrivibrio sp. was isolated in 1957 from the rumen of a heifer fed on silage. Both cultures used in this work were obtained from freeze-dried samples prepared soon after the original isolations. Stock cultures were maintained on the medium described below, solidified with 2% of agar and containing xylose instead of the wheat-flour pentosan.Subcultures were made once a month and stored in the refrigerator. Cultures were incubated at 380.The bacteria from two 2-day slope cultures on pentosan medium, suspended in sterile 09% NaCl, were used as inoculum for each 250 ml. of liquid culture.Preparation of media. The following stock solutions were used in preparing the culture media: I, 0-3 % K2HPO4.II, A solution containing 0-3 % of KH,PO,, 0-6% of (NH4)2SO4, 0-6 % of NaCl, 0-06 % of MgSO4,7H2O and 0-06% of CaCl,. III, A solution of 0-625% of cysteine hydrochloride and 6 % of NaHCO3 . IV, 2-5 % (w/v) wheatflour pentosan. Solution III was sterilized by passage through a Seitz filter and solution IV by steaming for 30 min. on 3 successive days. Bottles of 300 ml. capacity, containing 250 ml. of liquid medium, were used for large-scale culture. Into each bottle were placed solutions I and II (37.5 ml. each), Difco yeast extract (1-25 g.), strained rumen liquor (25 ml.), 0-1% solution of resazurin sodium (L. Light and Co. Ltd.; 0-25 ml.) and wate...

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